Multichip integration with through silicon via (tsv) die embedded in package

ABSTRACT

Embodiments of the present disclosure are directed to integrated circuit (IC) package assemblies with three-dimensional (3D) integration of multiple dies, as well as corresponding fabrication methods and systems incorporating such 3D IC package assemblies. A bumpless build-up layer (BBUL) package substrate may be formed on a first die, such as a microprocessor die. Laser radiation may be used to form an opening in a die backside film to expose TSV pads on the back side of the first die. A second die, such as a memory die stack, may be coupled to the first die by die interconnects formed between corresponding TSVs of the first and second dies. Underfill material may be applied to fill some or all of any remaining gap between the first and second dies, and/or an encapsulant may be applied over the second die and/or package substrate. Other embodiments may be described and/or claimed.

FIELD

Embodiments of the present disclosure generally relate to the field ofintegrated circuits, and more particularly, to techniques andconfigurations for enabling integrated circuit (IC) package assemblieswith three-dimensional (3D) integration of multiple dies.

BACKGROUND

While form factors continue to shrink in size, consumer demand forfaster processing speeds and increased memory capacity in mobile devicescontinues to rise. Recently, the IC industry has begun to practicethree-dimensional (3D) integration of flip chip packages and peripheraldevices using package-on-package (PoP) or direct die-to-dieinterconnection with through silicon vias (TSVs). However, currentlyavailable technologies do not provide for the use of thinner packagesubstrates such as bumpless build-up layers in 3D integration schemes.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example and not by wayof limitation in the figures of the accompanying drawings.

FIGS. 1 a-1 c illustrates a schematic cross-section side view of anexample integrated circuit (IC) package assembly and portions thereof,in accordance with various embodiments.

FIG. 2 schematically illustrates a flow diagram for a method offabricating an IC package assembly, in accordance with some embodiments.

FIGS. 3 a-3 g schematically illustrate various stages of IC packageassembly fabrication, in accordance with various embodiments.

FIG. 4 schematically illustrates a flow diagram for a method offabricating an IC package assembly, in accordance with some embodiments.

FIGS. 5 a-5 f schematically illustrate various stages of IC packageassembly fabrication, in accordance with various embodiments.

FIGS. 6 a-6 f schematically illustrate various stages of IC packageassembly fabrication, in accordance with various embodiments.

FIG. 7 schematically illustrates a computing device in accordance withvarious embodiments.

DETAILED DESCRIPTION

Embodiments of the present disclosure describe techniques andconfigurations for 3D multichip integration in IC package assemblies. Inthe following description, various aspects of the illustrativeimplementations will be described using terms commonly employed by thoseskilled in the art to convey the substance of their work to othersskilled in the art. However, it will be apparent to those skilled in theart that embodiments of the present disclosure may be practiced withonly some of the described aspects. For purposes of explanation,specific numbers, materials and configurations are set forth in order toprovide a thorough understanding of the illustrative implementations.However, it will be apparent to one skilled in the art that embodimentsof the present disclosure may be practiced without the specific details.In other instances, well-known features are omitted or simplified inorder not to obscure the illustrative implementations.

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, wherein like numeralsdesignate like parts throughout unless otherwise indicated, and in whichis shown by way of illustration embodiments in which the subject matterof the present disclosure may be practiced. It is to be understood thatother embodiments may be utilized and structural or logical changes maybe made without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of embodiments is defined by the appendedclaims and their equivalents.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and C).

The description may use perspective-based descriptions such astop/bottom, in/out, over/under, and the like. Such descriptions aremerely used to facilitate the discussion and are not intended torestrict the application of embodiments described herein to anyparticular orientation.

The description may use the phrases “in an embodiment,” or “inembodiments,” which may each refer to one or more of the same ordifferent embodiments. Furthermore, the terms “comprising,” “including,”“having,” and the like, as used with respect to embodiments of thepresent disclosure, are synonymous.

The term “coupled with,” along with its derivatives, may be used herein.“Coupled” may mean one or more of the following. “Coupled” may mean thattwo or more elements are in direct physical or electrical contact.However, “coupled” may also mean that two or more elements indirectlycontact each other, but yet still cooperate or interact with each other,and may mean that one or more other elements are coupled or connectedbetween the elements that are said to be coupled with each other. Theterm “directly coupled” may mean that two or elements are in directcontact.

In various embodiments, the phrase “a first feature formed, deposited,or otherwise disposed on a second feature,” may mean that the firstfeature is formed, deposited, or disposed over the second feature, andat least a part of the first feature may be in direct contact (e.g.,direct physical and/or electrical contact) or indirect contact (e.g.,having one or more other features between the first feature and thesecond feature) with at least a part of the second feature.

For ease of reference, IC package assembly components illustrated in theFigures are labeled with three-digit numbers in which the first digitcorresponds to the Figure number (e.g., features of FIGS. 1 a-1 c arelabeled “1XX”) and the second and third digits identify the component.Therefore, while an IC package assembly component may be described withreference to a particular Figure (e.g., first die 102 a of FIGS. 1 a-1c), the description should be understood to apply equally tocorresponding components of other Figures. For example, first die 302 aof FIGS. 3 a-3 g, first die 502 a of FIGS. 5 a-5 g, first die 602 a ofFIGS. 6 a-6 f, and first die 702 a of FIG. 7 may have any or all of thefeatures/configuration described for first die 102 a of FIGS. 1 a-1 c.

As used herein, the phrase “through-silicon via” or “TSV” may be used inreference to an electrically conductive through-hole that extends atleast partially through a die or other semiconductor substrate/device,such as an interposer. The phrase “through-silicon via” or “TSV” may beused for such electrically conductive features even when thesemiconductor material is composed of a material other than silicon.

Embodiments described herein provide three-dimensional (3D) integratedcircuit (IC) package assembly configurations and correspondingfabrication techniques. In various embodiments, an IC package assemblymay include a first die embedded in a package substrate, a second diecoupled with the first die, and an adhesive layer disposed between thefirst and second dies. The first die may be such as a microprocessor/CPUwith one or more TSVs, and the package substrate may be a BumplessBuild-Up Layer (BBUL) package substrate. In some embodiments, thepackage substrate may be a coreless substrate. In various embodiments,the second die may be a memory die stack with multiple memory diescoupled by TSVs, and the adhesive layer may be a die backside film (DBF)layer. In various embodiments, an opening may be formed in the adhesivelayer. A TSV pad on the first die and a TSV pad on the second die may bepositioned on opposite sides of the opening and coupled with a dieinterconnect to form a conductive path. In some embodiments, anencapsulant may be applied over the second die, and/or an underfillmaterial may be used to fill the opening in the adhesive layer or otherremaining space between the adhesive layer and the second die.

In some embodiments, the opening may be formed in the adhesive layerbefore the package substrate is formed on the first die. In otherembodiments, the opening may be formed in the adhesive layer after thepackage substrate is formed. In various embodiments, the opening may beformed by selectively exposing a portion of the adhesive layer to laserenergy with a laser patterning projection (LPP) tool. In otherembodiments, the laser energy may be applied by scanning the adhesivelayer or portion thereof with a laser scanning system (e.g., a galvanoscanner). In various embodiments, the laser may be a UV laser.

FIGS. 1 a-1 c depict schematic side cross-sectional views of anintegrated circuit (IC) package assembly 100, in accordance with variousembodiments. Referring first to FIG. 1 a, IC package assembly 100 mayinclude a first die 102 a embedded in a package substrate 104, a seconddie 102 b coupled with first die 102 a, and a circuit board 122 coupledwith package substrate 104. In some embodiments, second die 102 b mayinclude a plurality of dies arranged in a stacked three-dimensional (3D)configuration (e.g., dies 140 of FIG. 1 b). In various embodiments,second die 102 b may include one or more memory dies.

In various embodiments, second die 102 b may be embedded in anencapsulant 108. Encapsulant 108 can be any suitable material, such as(but not limited to) an Ajinomoto Build-up Film (ABF) substrate or otherbuild-up film, other dielectric/organic materials, resins, epoxies,polymer adhesives, silicones, acrylics, polyimides, cyanate esters,thermoplastics, and/or thermosets.

In some embodiments, first die 102 a and second die 102 b may besingulated dies. In other embodiments, first die 102 a and/or second die102 b may include two or more dies arranged in a stack. In otherembodiments, first die 102 a and/or second die 102 b may be a wafer (orportion thereof) having two or more dies formed thereon.

In various embodiments, first die 102 a and/or second die 102 b may be aprimary logic die. In other embodiments, first die 102 a and/or seconddie 102 b may be configured to function as memory, an applicationspecific circuit (ASIC), a processor, or some combination thereof. Insome embodiments, first die 102 a may be a CPU/processor and second die102 b may be one or more memory dies.

In some embodiments, an interface layer 124 may be provided betweenfirst die 102 a and second die 102 b. Interface layer 124 may be, or mayinclude, a layer of underfill, adhesive, dielectric, or other material.Interface layer 124 may serve various functions, such as providingmechanical strength, conductivity, heat dissipation, or adhesion.

In some embodiments, package substrate 104 may be a coreless substrate.For example, package substrate 104 may be a bumpless build-up layer(BBUL) assembly that includes a plurality of “bumpless” build-up layers.As used herein, “bumpless build-up layers” may refer to layers ofsubstrate and components embedded therein without the use of solder orother attaching means that may be considered “bumps.” In variousembodiments, one or more build-up layers described herein may havematerial properties that may be altered and/or optimized forreliability, warpage reduction, and so forth. In other embodiments,package substrate 104 may be composed of a polymer, ceramic, glass, orsemiconductor material. In some embodiments, package substrate 104 maybe a conventional cored substrate and/or an interposer.

First die 102 a may be coupled to a first side of package substrate 104.In various embodiments, first die 102 a may be embedded in packagesubstrate 104. A second opposite side of package substrate 104 may becoupled to circuit board 122 by package interconnects 112. Packageinterconnects 112 may couple electrical routing features 110 disposed onthe second side of package substrate 104 to corresponding electricalrouting features 116 on circuit board 122. Package substrate 104 mayhave conductive features 134, such as traces, trenches, and/or vias,formed therein to route electrical signals between the first/second die102 a/102 b and circuit board 122 and/or other electrical componentsexternal to the IC package assembly 100. Package interconnects 112 mayinclude any of a wide variety of suitable structures and/or materialsincluding, for example, bumps, pillars or balls formed using metals,alloys, solderable material, or combinations thereof. In variousembodiments, electrical routing features 110 may be arranged in a ballgrid array (BGA) or other configuration.

In some embodiments, circuit board 122 may be a printed circuit board(PCB) composed of an electrically insulative material such as an epoxylaminate. For example, the circuit board 122 may include electricallyinsulating layers composed of materials such as, for example,polytetrafluoroethylene, phenolic cotton paper materials such as FlameRetardant 4 (FR-4), FR-1, cotton paper and epoxy materials such as CEM-1or CEM-3, or woven glass materials that are laminated together using anepoxy resin prepreg material. The circuit board 122 may be composed ofother suitable materials in other embodiments.

Some portions/features of circuit board 122 may not be depicted in FIG.1 a. In various embodiments, the circuit board 122 may include otherelectrical devices coupled to the circuit board that are configured toroute electrical signals to or from first/second die 102 a/102 b throughthe circuit board 122. In some embodiments, circuit board 122 mayinclude structures such as traces, trenches, and/or vias formed thereinto route electrical signals through the circuit board 122. In someembodiments, the circuit board 122 may be a motherboard (e.g.,motherboard 722 of FIG. 7).

FIG. 1 b depicts a schematic side cross-sectional view of a die portionof IC package assembly 100, in accordance with various embodiments. Asillustrated, first die 102 a may have a first side S1 and a second sideS2 opposite to the first side S1. First side S1 may be the side of thedie commonly referred to as the “active” or “top” or “front” side of thedie. First side S1 may include one or more transistors. Second side S2may be the side of the die commonly referred to as the “inactive” or“bottom” or “back” side of the die.

First side S1 may include an active layer 114 with one or moretransistors formed thereon. The one or more transistors may be locatedbelow the outer surface of first side S1 and are routed to the outersurface of first side S1 by a series of metal and oxide layers. Secondside S2 may include a semiconductor substrate 118 composed of asemiconductor material. The semiconductor substrate 118 may be composedof n-type or p-type material systems and may include, for example, acrystalline substrate formed using a bulk silicon or asilicon-on-insulator substructure. In some embodiments, thesemiconductor substrate 118 may be formed using alternate materials,which may or may not be combined with silicon, that include but are notlimited to germanium, indium antimonide, lead telluride, indiumarsenide, indium phosphide, gallium arsenide, or gallium antimonide.Other group II-VI, III-V or group IV material systems may also be usedto form the semiconductor substrate 118 according to variousembodiments.

In various embodiments, first die 102 a may include one or morethrough-silicon vias (TSVs) 126 formed at least partially throughsemiconductor substrate 118. First side S1 of first die 102 a mayinclude electrical routing features 106. In some embodiments, electricalrouting features 106 may be bond pads. Second side S2 may also includeone or more electrical routing features 128. In some embodiments,electrical routing features 128 may be TSV pads coupled to correspondingTSVs 126. TSVs 126 may be configured to route electrical signals betweenthe active layer 114 on first side S1 and the electrical routingfeatures 128 on second side S2 of die 102 a.

In some embodiments, second die 102 b may include a plurality of dies140 and one or more TSVs 136 disposed through some or all of the dies140. In various embodiments, electrical routing features 138 may beprovided on one or more of the dies 140 of second die 102 b. One or moreof the electrical routing features 138 may be electrically coupled witha corresponding TSV 136. The dies 140 may be coupled together using anysuitable technique including, for example, interconnect structures suchas, for example, pads, bumps, pillars, solderable material, orcombinations thereof. That is, the TSVs 136 may not be composed of asingle, contiguous material structure as depicted in some embodiments.

Electrical routing features 128/138 may be electrically conductive pads,bumps, pillars, or other such structures. In various embodiments,electrical routing features 128/138 may have one or more layers ofmetal, including but not limited to nickel, palladium, platinum, tin,silver, gold, copper, or other metals, alone or in any combination. Insome embodiments, electrical routing features 128 may have one or morelayers of copper. In other embodiments, electrical routing features 138may have an outer surface of gold.

The electrical routing features 138 of second die 102 b may be coupledwith the electrical routing features 128 of first die 102 a by dieinterconnects 120. In various embodiments, die interconnects 120 may beformed using a solderable material (e.g., solder paste, solder balls).In some embodiments, a first TSV 126 of first die 102 a may be coupledwith a second TSV 136 of second die 102 b by corresponding electricalrouting features 128/138 and die interconnect 120 to form a conductivepath 142 that extends at least partially through first die 102 a andsecond die 102 b. Conductive path 142 may route electrical signalsbetween second die 102 b and first die 102 a. In some embodiments, theelectrical signals may include, for example, input/output (I/O) signalsand/or power or ground signals associated with the operation of firstdie 102 a/second die 102 b.

Second die 102 b may be coupled to first die 102 a in a front-to-backconfiguration (e.g., the “front” or “active” side of second die 102 bcoupled to the “back” or “inactive” side S1 of first die 102 a), asshown for example in FIG. 1 b. In other configurations, first and seconddies 102 a/102 b may be coupled with one another in a back-to-backarrangement. In various embodiments, one or more additional dies may becoupled with first die 102 a, second die 102 b, and/or with packagesubstrate 104.

In some embodiments, an adhesive layer 130 may be disposed on the secondside S2 of first die 102 a. Adhesive layer 130 may include a polymermatrix. Examples of suitable materials for adhesive layer 130 mayinclude, but are not limited to, epoxy, acrylic, polyimide,epoxy-acrylate, other polymer materials, and combinations thereof. Invarious embodiments, adhesive layer 130 may be a die backside film(DBF).

In some embodiments, adhesive layer 130 may include an opening 132, andone or more of the electrical routing features 128 and/or dieinterconnects 120 may be positioned within opening 132. In someembodiments, an opening 132 may correspond to the entire adhesive layer130. For example, in some IC package assemblies, forming opening 132 mayinclude removing the entire adhesive layer 130.

As illustrated for example in FIGS. 1 a-1 b, an interface layer 124 maybe formed between first die 102 a and second die 102 b by adding anunderfill material or other suitable material into opening 132 and/orbetween adhesive layer 130 and second die 102 b. One or both ofinterface layer 124 and adhesive layer 130 may impart mechanicalstrength/warpage resistance to IC package assembly 100. Again, someembodiments may lack adhesive layer 130 and opening 132. For example, insome embodiments, adhesive layer 130 may be applied to first die 102 aat one stage of IC package assembly fabrication, and subsequentlyremoved before fabrication is completed.

Spacing/pitch of features such as electrical routing features 128/138and die interconnects 120 may vary among embodiments. In someembodiments, the distance between adjacent electrical routing features128 and/or adjacent electrical routing features 138 may be in the rangeof 30-80 μm, 40-100 μm, less than 40 μm, or more than 100 μm.

Referring now to FIG. 1 c, dimensions of features such as electricalrouting features 128/138, adhesive layer 130, and die interconnects 120may vary among embodiments.

In various embodiments, adhesive layer 130 may have a thickness (ArrowA) of less than 10 μm. In other embodiments, adhesive layer 130 may havea thickness (Arrow A) in the range of 0.1-20 μm, 0.1-9.9 μm, 1-9.9 μm,or 5-9.9 μm.

In various embodiments, electrical routing features 128 may have a width(Arrow B) of 20 μm and a height/thickness (Arrow C) of 3 μm. In otherembodiments, electrical routing features 128 may have a width (Arrow B)in the range of 5-40 μm, 10-30 μm, or 15-25 μm, and a height/thickness(Arrow C) in the range of 0.5-15 μm, 1-10 μm, or 2-5 μm.

In various embodiments, electrical routing features 138 may have a width(Arrow D) of 20 μm and a height/thickness (Arrow E) of 10 μm. In otherembodiments, electrical routing features 138 may have a width (Arrow D)in the range of 5-40 μm, 10-30 μm, or 15-25 μm, and a height/thickness(Arrow E) in the range of 1-20 μm, 5-15 μm, or 8-12 μm.

In various embodiments, die interconnect 120 may have a height/thickness(Arrow F) of 10 μm. In other embodiments, die interconnect 120 may havea height/thickness (Arrow F) in the range of 1-20 μm, 5-15 μm, or 8-12μm.

In a particular embodiment, adhesive layer 130 may have a thickness(Arrow A) of less than 10 μm, electrical routing features 128 may have awidth (Arrow B) of 20 μm and a height/thickness (Arrow C) of 3 μm,electrical routing features 138 may have a width (Arrow D) of 20 μm anda height/thickness (Arrow E) of 10 μm, and die interconnect 120 may havea height/thickness (Arrow F) of 10 μm.

In various embodiments, adhesive layer 130 may be applied to the secondside S2 of first die 102 a and subsequently coupled with a sacrificialpanel. A package substrate (e.g., package substrate 104) may then beformed on, or coupled with, the first side S1 of first die 102 a, andthe sacrificial panel may then be removed. In some embodiments, adhesivelayer 130 may cover electrical routing features 128 during the build-upprocess, and opening 132 may be formed through adhesive layer 130 toexpose electrical routing features 128 after removal of the sacrificialpanel. In other embodiments, opening 132 may be formed in adhesive layer130 before applying adhesive layer 130 to first die 102 a, and adhesivelayer 130 may be positioned on second side S2 such that one or more ofthe electrical routing features 138 are within opening 132. In suchembodiments, electrical routing features 128 may be exposed by removalof the sacrificial panel after the build-up process. In any case, seconddie 102 b may be coupled with first die 102 a after electrical routingfeatures 138 have been exposed.

In other embodiments, adhesive layer 130 may be coupled with thesacrificial panel, and opening 132 may be formed in adhesive layer 130,before coupling first die 102 a with adhesive layer 130. Opening 132 maybe formed in adhesive layer 130 either before or after adhesive layer130 is coupled with the sacrificial panel. First die 102 a may then becoupled with adhesive layer 130 by positioning second side S2 onadhesive layer 130 such that one or more of the electrical routingfeatures 128 is disposed within opening 132. Package substrate 104 maythen be formed on, or otherwise coupled with, the first side S1 of firstdie 102 a. The sacrificial panel may then be removed to exposeelectrical routing features 128. In other embodiments, adhesive layer130 may cover electrical routing features 128 during the build-upprocess, and opening 132 may be formed in adhesive layer 130 after theformation of the build-up layers and removal of the sacrificial panel.In any case, as described more fully below, opening 132 may be formed byexposure of adhesive layer 130 to radiation energy.

FIGS. 2 and 4 schematically illustrate flow diagrams for methods offabricating an IC package assembly, in accordance with some embodiments.FIGS. 3 a-3 g depict various stages of fabrication corresponding to themethods illustrated in FIG. 2. FIGS. 5 a-5 f and FIGS. 6 a-6 f depictvarious stages of fabrication corresponding to methods illustrated inFIG. 4.

While some Figures illustrate fabrication processes on only one side ofa sacrificial panel for ease of reference, it is to be understood thatany of the methods described herein may be performed on opposite sidesof the same sacrificial panel and/or along multiple portions of the sameside of the sacrificial panel.

Referring first to FIG. 2, method 200 may be begin at block 201 withproviding a first die having a first side with one or more transistors,a second side with an electrical routing feature (e.g., electricalrouting feature 128), and a first TSV (e.g., TSV 126) coupled to theelectrical routing feature.

At block 203, an adhesive layer may be coupled with the second side ofthe first die. FIG. 3 a illustrates a corresponding stage of fabricationof an IC package assembly 300. As illustrated, adhesive layer 330 may becoupled with the second side S2 of first die 302 a and may cover one ormore electrical routing features 328. In various embodiments, electricalrouting features 328 may be TSV pads, and a first TSV 326 may beconductively coupled to a TSV pad 328. In various embodiments, adhesivelayer 330 may be coupled with first die 302 a either before or afterfirst die 302 a is singulated from a wafer.

At block 205, the adhesive layer may be coupled to a sacrificial panel.As shown for example in FIG. 3 b, sacrificial panel 346 may have one ormore layers arranged in a stacked configuration. For example,sacrificial panel 346 may include an epoxy core disposed between one ormore outer layers of a metal, such as copper foil. In particularembodiments, one or more of the outer layers of sacrificial panel 346may be configured to remain adhered to adhesive layer 330 as otherlayers are mechanically peeled away. The outer layer(s) may besubsequently removed from adhesive layer 330 by a conventional etchingprocess.

At block 207, one or more build-up layers may be formed on the firstside of the first die. FIG. 3 c illustrates a corresponding stage offabrication of IC package assembly 300 with a coreless package substrate304 that includes a plurality of build-up layers 350, 352, 354, and 356.The number and configuration of build-up layers may vary amongembodiments. While four build-up layers are illustrated by way ofexample, in other embodiments package substrate 304 may have one, two,three, or more than four build-up layers. In some embodiments, thebuild-up layer(s) may be formed sequentially on first die 302 a. Inother embodiments, package substrate 304 may be formed in a separateprocess and subsequently coupled with first die 302 a.

In some embodiments, the first build-up layer 350 may be formed bylaminating a layer of dielectric material (e.g., ABS film) onto thefirst side S1 of first die 302 a, drilling vias through the dielectricmaterial (e.g., by laser drilling) to electrical routing features 306,filling/plating the vias with an electrically conductive material (e.g.,copper), and forming electrically conductive traces on the dielectricmaterial and vias by known methods. Additional build-up layers 352, 354,and 356 may be formed sequentially in the same or similar manner.Openings may be drilled in the outermost layer 356 to one or more of theconductive features (e.g., conductive features 334 such as vias ortraces, or electrical routing features 110 of FIG. 1 a), and packageinterconnects 312 may be formed in the openings. In some embodiments,adhesive layer 330 may be cured as the build-up layers are formed (e.g.,cured by heat, pressure, and/or UV light).

At block 209, the sacrificial panel may be removed from the adhesivelayer, exposing the adhesive layer. In various embodiments, some portionof the sacrificial layer, such as an epoxy core, may be peeled away fromanother portion (e.g., layer of copper foil) that remains adhered to theadhesive layer. This remaining portion may be removed by a conventionaletching process. FIG. 3 d illustrates a corresponding stage offabrication, in which the sacrificial panel 346 has been removed fromadhesive layer 330 and package substrate 304.

At block 211, an opening may be formed in the adhesive layer to exposethe electrical routing feature. FIG. 3 e illustrates a correspondingstage of fabrication, in accordance with various embodiments. Asillustrated, laser radiation source 358 may be used to selectivelyablate a portion of adhesive layer 330, thereby forming an opening 332in adhesive layer 330 to expose electrical routing features 328. Invarious embodiments, laser radiation 360 may be ultraviolet (UV) laserradiation, and laser radiation source 358 may be a carbon dioxide (CO2)laser, a carbon monoxide (CO) laser, a neodymium-doped yttrium aluminumgarnet (Nd:YAG) laser in various harmonics, an excimer laser, or anyother suitable type of laser radiation source. In some embodiments,laser radiation source 358 may be a pulsed laser. In other embodiments,laser radiation source 358 may be a continuous laser. In someembodiments, laser radiation 360 may be laser radiation of a shortvisible wavelength, such as green (e.g., 532 nm).

In various embodiments, opening 332 may be formed by ablating some orall of adhesive layer 330 with a beam scanner-based system or a maskprojector-based system. In various embodiments, opening 332 may beformed by laser projection patterning (LPP). LPP may be used in someembodiments to expose the entire selected area without scanning/skivingand at a relatively low fluence (e.g., 0.3-0.8 J/cm²) with little or nodamage to electrical routing features 328. In other embodiments, agalvano scanner may be used to controllably remove the selected areawith the laser radiation to form opening 332. Again, the laser radiationmay have a relatively low fluence that is below a laser damage thresholdfor electrical routing features 328 and/or second side S2 of first die302 a. In some embodiments, all of adhesive layer 330 may be removed.

In some embodiments, block 211 may further include a desmear process toremove any remaining substrate residue from electrical routing features328. In other embodiments, block 211 may further include a cleaningprocess (e.g., with flux) to remove oxidation/contaminants from theouter surface of electrical routing features 328. Other embodiments mayomit one or both of the desmear/cleaning processes.

At block 213, a second die may be coupled with the second side of thefirst die, with the adhesive layer disposed between the first die andthe second die. In various embodiments, second die 302 b may be coupledwith first die 302 a using a die attach tool, or by other techniquessuitable for use in fine pitch applications (e.g., bump pitches of lessthan 100 μm) such as thermal compression bonding (TCB). In someembodiments, solder balls may be used to couple TSVs of the first die toTSVs of the second die.

FIG. 3 f illustrates a corresponding stage of fabrication. Asillustrated, second die 302 b may have one or more TSVs 336 and firstdie 302 a may have one or more TSVs 326. A die interconnect 320 (e.g., asolder) may be formed between a first TSV 326 of first die 302 a and asecond TSV 336 of second die 302 b. TSVs 326 and 336, electrical routingfeatures 328/138 (see FIGS. 3 f and 1 b, respectively), and dieinterconnect 320 may collectively form a conductive path (e.g.,conductive path 142, FIG. 1 b) that extends through opening 332 ofadhesive layer 330. In some embodiments, die interconnect 320 may beformed by conventional methods, such as by solder paste printing/reflowtechniques.

At block 215, an underfill material may be placed into the openingbetween the first die and the second die. At block 217, an encapsulant(e.g., a molding material) may be applied over the second die and theone or more build-up layers. FIG. 3 g illustrates a corresponding stageof fabrication. As illustrated, underfill material may be added betweenfirst die 302 a and second die 302 b to form an interface layer 324.Interface layer 324 may substantially fill opening 332 and/or remainingspace between second die 302 b and adhesive layer 330. In someembodiments, all of adhesive layer 330 may be removed in block 209, andunderfill material may be used to fill some or all of the space betweenfirst die 302 a and second die 302 b. In other embodiments, encapsulant308 may be formed over second die 302 b and/or package substrate 304.

Some embodiments may include both blocks 215 and 217. In otherembodiments, one or both of blocks 215 and 217 may be omitted. Forexample, in some embodiments, block 215 may be omitted. In otherembodiments, block 217 may be omitted. In still other embodiments, bothblock 215 and block 217 may be omitted.

In other embodiments, an adhesive layer may be patterned to form theopening before coupling the first die with the adhesive layer, such thatthe adhesive layer does not contact the electrical routing features(e.g., TSV pads). FIG. 4 illustrates an example of such an embodiment.FIGS. 5 a-5 g and 6 a-6 g illustrate two variations of the embodiment ofFIG. 4.

Referring now to FIG. 4, method 400 may be begin at block 401 withproviding a first die (e.g., first die 102 a of FIG. 1) having a firstside with one or more transistors, a second side with an electricalrouting feature (e.g., electrical routing feature 128), and a first TSV(e.g., TSV 126) coupled to the electrical routing feature.

At block 403, an adhesive layer may be coupled to a sacrificial panel.In some embodiments, as illustrated by way of example in FIG. 5 a, block403 may include forming an outermost copper layer 570 on a sacrificialpanel 546 and forming an opening 572 in the outermost copper layer 570.Adhesive layer 530 may be positioned within the opening 572 byconventional techniques, such as with a pick-and-place tool.

Alternatively, as illustrated by way of example in FIG. 6 a, adhesivelayer 630 may be coupled with a sacrificial panel 646 without formingoutermost copper layer 570 or opening 572.

At block 405, an opening may be formed in the adhesive layer. As shownby way of example in FIGS. 5 b and 6 b, openings 532/632 may be formedin adhesive layer 530/630 by using a laser radiation source 558/658 toexpose a selected area of adhesive layer 530/630 to laser radiation560/660.

At block 407, the adhesive layer may be coupled to the second side ofthe first die, with the electrical routing feature positioned in theopening. FIGS. 5 c and 6 c illustrate corresponding stages offabrication. As illustrated, positioning first die 502 a/602 a withelectrical routing features 528/628 in opening 532/632 may reduce oreliminate contact between electrical routing features 528/628 andadhesive layer 530/630. This may reduce or eliminate the need for asubsequent descum process.

At block 409, one or more build-up layers may be formed on the firstdie. FIGS. 5 d and 6 d illustrate corresponding stages of fabrication.As illustrated, a package substrate 504/604 (e.g., a BBUL substrate withone or more build-up layers) may be formed sequentially on first die 502a/602 a and electrical routing features 506/606.

At block 411, the sacrificial panel may be removed from the IC packageassembly as described above in connection with block 209 of FIG. 2.

Blocks 413, 415, and 417 may be performed in the same or similar manneras described with reference to blocks 213, 215, and 217 of FIG. 2.

At block 413, illustrated by way of example in FIGS. 5 e and 6 e, asecond die 502 b/602 b may be coupled with the second side of the firstdie 502 a/602 a. Adhesive layer 530/630 may be disposed between thefirst die 502 a/602 a and the second die 502 b/602 b. In variousembodiments, second die 502 b/602 b may be coupled with first die 502a/602 a using a die attach tool, or by other techniques such as thermalcompression bonding (TCB).

A die interconnect 520/620 (e.g., a solder ball) may be formed between afirst TSV 526/626 of first die 502 a/602 a and a second TSV 536/636 ofsecond die 502 b/602 b. TSVs 526/626 and 536/636, electrical routingfeatures 528/628, corresponding electrical routing features of seconddie 502 b/602 b (see e.g., electrical routing features 138, FIG. 1 b),and die interconnect 520/620 may collectively form a conductive path(see e.g., conductive path 142, FIG. 1 b) that extends through opening532/632 of adhesive layer 530/630. In some embodiments, die interconnect520/620 may be formed by conventional methods, such as by solder pasteprinting/reflow techniques.

At block 415, an underfill material may be placed into the openingbetween the first die and the second die. At block 417, an encapsulant(e.g., a molding material) may be applied over the second die and theone or more build-up layers. FIGS. 5 f and 6 f illustrate correspondingstages of fabrication. In various embodiments, underfill material may beused to form an interface layer 524/624. In other embodiments,encapsulant 508/608 may be formed over second die 502 b/602 b and/orpackage substrate 504/604. Again, some embodiments may include bothblocks 415 and 417. In other embodiments, one or both of blocks 415 and417 may be omitted. For example, in some embodiments, block 415 may beomitted. In other embodiments, block 417 may be omitted. In still otherembodiments, both block 415 and block 417 may be omitted.

Various operations are described as multiple discrete operations inturn, in a manner that is most helpful in understanding the claimedsubject matter. However, the order of description should not beconstrued as to imply that these operations are necessarily orderdependent. Embodiments of the present disclosure may be implemented intoa system using any suitable hardware and/or software to configure asdesired.

FIG. 7 illustrates an example computing device 701, in accordance withvarious embodiments. IC package assemblies as described herein may beinstalled on a computing/communicating device. For example, IC packageassembly 700 may be installed on a computing device 701. IC packageassembly 700 may include a first die 702 a embedded in a packagesubstrate 704 and a second die 702 b coupled with the first die 702 a.Components, features, and/or configurations of IC package assembly 700may be as described herein with reference to any of IC packageassemblies 100, 300, 500, and/or 600.

The computing device 701 may house a circuit board such as motherboard722. The motherboard 722 may include a number of components, includingbut not limited to IC package assembly 700 and at least onecommunication chip 762. The IC package assembly 700 may be physicallyand electrically coupled to the motherboard 722 (e.g., circuit board 122of FIG. 1). In some implementations, communication chip(s) 762 may alsobe physically and electrically coupled to the motherboard 722. Infurther implementations, the communication chip(s) 762 may be part ofthe IC package assembly 700. In various embodiments, at least onecommunication chip 762 may be physically and electrically coupled to ICpackage assembly 700. In further implementations, a communication chip762 may be part of IC package assembly 700, e.g., as an additional dieon or embedded in build-up layers in IC package assembly 700. For theseembodiments, IC package assembly 700 and communication chip 762 may bedisposed on the motherboard 722. In alternate embodiments, the variouscomponents may be coupled without the employment of motherboard 722.

In some embodiments, a die of IC package assembly 700 (e.g., first die702 a) may be a processor of the computing device 701. The term“processor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be stored inregisters and/or memory.

Depending on its applications, computing device 701 may include othercomponents that may or may not be physically and electrically coupled tothe motherboard 722. These other components include, but are not limitedto, volatile memory (e.g., dynamic random access memory, also referredto as “DRAM”), non-volatile memory (e.g., read only memory, alsoreferred to as “ROM”), flash memory, an input/output controller, adigital signal processor (not shown), a crypto processor (not shown), agraphics processor, one or more antenna, a display (not shown), a touchscreen display, a touch screen controller, a battery, an audio codec(not shown), a video codec (not shown), a global positioning system(“GPS”) device, a compass, an accelerometer (not shown), a gyroscope(not shown), a speaker, a camera, and a mass storage device (such ashard disk drive, a solid state drive, compact disk (“CD”), digitalversatile disk (“DVD”))(not shown), micromirrors (not shown), and soforth. In various embodiments, various components may be integrated withother components to form a System on Chip (“SoC”). In furtherembodiments, some components, such as DRAM, may be embedded in or withinIC package assembly 700.

The communication chip(s) 762 may enable wired and/or wirelesscommunications for the transfer of data to and from the computing device701. The term “wireless” and its derivatives may be used to describecircuits, devices, systems, methods, techniques, communicationschannels, etc., that may communicate data through the use of modulatedelectromagnetic radiation through a non-solid medium. The term does notimply that the associated devices do not contain any wires, although insome embodiments they might not. The communication chip 762 mayimplement any of a number of wireless standards or protocols, includingbut not limited to Institute for Electrical and Electronic Engineers(IEEE) standards including Wi-Fi (IEEE 802.11 family), IEEE 802.16standards (e.g., IEEE 802.16-2005 Amendment), Long-Term Evolution (LTE)project along with any amendments, updates, and/or revisions (e.g.,advanced LTE project, ultra mobile broadband (UMB) project (alsoreferred to as “3GPP2”), etc.). IEEE 802.16 compatible BWA networks aregenerally referred to as WiMAX networks, an acronym that stands forWorldwide Interoperability for Microwave Access, which is acertification mark for products that pass conformity andinteroperability tests for the IEEE 802.16 standards. The communicationchip 762 may operate in accordance with a Global System for MobileCommunication (GSM), General Packet Radio Service (GPRS), UniversalMobile Telecommunications System (UMTS), High Speed Packet Access(HSPA), Evolved HSPA (E-HSPA), or LTE network. The communication chip762 may operate in accordance with Enhanced Data for GSM Evolution(EDGE), GSM EDGE Radio Access Network (GERAN), Universal TerrestrialRadio Access Network (UTRAN), or Evolved UTRAN (E-UTRAN). Thecommunication chip 762 may operate in accordance with Code DivisionMultiple Access (CDMA), Time Division Multiple Access (TDMA), DigitalEnhanced Cordless Telecommunications (DECT), Evolution-Data Optimized(EV-DO), derivatives thereof, as well as any other wireless protocolsthat are designated as 3G, 4G, 5G, and beyond. The communication chip762 may operate in accordance with other wireless protocols in otherembodiments.

The computing device 701 may include a plurality of communication chips762. For instance, a first communication chip 762 may be dedicated toshorter range wireless communications such as Wi-Fi and Bluetooth and asecond communication chip 762 may be dedicated to longer range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, andothers.

In various implementations, the computing device 701 may be a laptop, anetbook, a notebook, an ultrabook, a smart phone, a computing tablet, apersonal digital assistant (“PDA”), an ultra mobile PC, a mobile phone,a desktop computer, a server, a printer, a scanner, a monitor, a set-topbox, an entertainment control unit (e.g., a gaming console), a digitalcamera, a portable music player, a digital video recorder, or a digitalwatch. In further implementations, the computing device 701 may be anyother electronic device that processes data.

EXAMPLES

Various embodiments of 3D IC package assemblies, methods for fabricatingsuch 3D IC package assemblies, and systems incorporating such 3D ICpackage assemblies are described herein. In various embodiments, apackage assembly may comprise a package substrate with a plurality ofbuild-up layers, a first die embedded in the package substrate, and asecond die coupled with the first die. In various embodiments, the firstdie may have a first side with one or more transistors, a second sideopposite to the first side, a first through silicon via (TSV), and anelectrical routing feature disposed on a first portion of the secondside. In various embodiments, the electrical routing feature may beelectrically coupled with the one or more transistors by the first TSV.

In various embodiments, the second die may have a second TSVelectrically coupled with the first TSV. In various embodiments, thepackage assembly may further include an adhesive layer disposed on asecond portion of the second side of the first die, and the electricalrouting feature may be disposed within an opening in the adhesive layer.In various embodiments, the second die may be a memory die. In variousembodiments, the electrical routing feature may a TSV pad. In variousembodiments, the first TSV may one of a first plurality of TSVs of thefirst die. In various embodiments, the second TSV may be one of a secondplurality of TSVs of the second die that correspond with and arearranged in vertical alignment with the first plurality of TSVs.

In various embodiments, the second die may be one of a plurality ofmemory dies configured in a three-dimensional (3D) memory die stack. Invarious embodiments, the electrical routing feature may be a first TSVpad. In various embodiments, the second die may have a second TSV padcoupled with the second TSV. In various embodiments, the packageassembly may further comprise a die interconnect coupled with the firstTSV pad and the second TSV pad. In various embodiments, the packageassembly may further comprise an underfill layer disposed between thefirst die and the second die. In various embodiments, an underfill layermay be disposed between the first die and the second die. In variousembodiments, an underfill layer may be disposed within the opening inthe adhesive layer. In various embodiments, a portion of the underfilllayer may be disposed between the adhesive layer and the first die. Invarious embodiments, the package assembly may further include a layer ofmolding material configured to encapsulate the second die.

In various embodiments, a method may comprise providing a first die,wherein the first die has a first side with one or more transistors, asecond side with an electrical routing feature, and a first throughsilicon via (TSV) coupled to the electrical routing feature and disposedbetween the first side and the second side, coupling an adhesive layerto the second side of the first die, forming one or more build-up layerson the first side of the first die, forming an opening in the adhesivelayer, and coupling a second die with the second side of the first die,with the adhesive layer disposed between the first die and the seconddie. In various embodiments, the second die may have a second TSV, andthe first TSV may be electrically coupled with the second TSV by aconductive path disposed through the opening. In various embodiments, amethod may further comprise coupling the adhesive layer to a sacrificialpanel prior to coupling the adhesive layer to the second side of thefirst die. In various embodiments, forming the opening in the adhesivelayer may include forming an opening through the adhesive layer to thesacrificial panel prior to coupling the adhesive layer to the secondside of the die. In various embodiments, coupling the adhesive layer tothe second side of the die may include placing the second side of thedie onto the adhesive layer with the electrical routing feature disposedin the opening.

In various embodiments, a method may further include forming a copperlayer on the sacrificial panel and forming a cavity in the copper layer.In various embodiments, coupling the adhesive layer to the sacrificialpanel may include placing the adhesive layer into the cavity prior toforming the opening through the adhesive layer to the sacrificial panel.In various embodiments, coupling the adhesive layer to the second sideof the first die may include placing a portion of the adhesive layer onthe electrical routing feature. In various embodiments, a method mayfurther include placing the first die and the adhesive layer onto asacrificial panel, with the adhesive layer disposed between the firstdie and the sacrificial panel, and removing the sacrificial panel fromthe adhesive layer after forming the one or more build-up layers on thefirst side of the die. In various embodiments, forming the opening inthe adhesive layer may include removing the portion of the adhesivelayer after removing the sacrificial panel to expose the electricalrouting feature. In various embodiments, forming the opening in theadhesive layer may include exposing a portion of the adhesive layer tolaser radiation. In various embodiments, exposing the portion of theadhesive layer to laser radiation may be performed by a laser projectionpatterning tool. In various embodiments, the laser projection patterningtool may include one or more excimer lasers.

In various embodiments, removing the portion of the adhesive layer mayfurther include scanning the portion of the adhesive layer with anultraviolet (UV) laser. In various embodiments, removing the portion ofthe adhesive layer may further include exposing the portion of theadhesive layer to laser radiation with an excimer laser. In variousembodiments, removing the portion of the adhesive layer may furtherinclude exposing the portion of the adhesive layer to laser radiation bylaser direct imaging. In various embodiments, removing the portion ofthe adhesive layer may further include exposing the portion of theadhesive layer to laser radiation by laser projection patterning. Invarious embodiments, the laser radiation may be UV or green laserradiation. In various embodiments, a method may further include applyinga molding material over the second die and the one or more build-uplayers. In various embodiments, the second die may be embedded in themolding material. In various embodiments, a method may further includeapplying an underfill material between the first die and the second die.

In various embodiments, a system may comprise a circuit board and apackage assembly coupled with the circuit board via electrical routingfeatures disposed on an outer surface of the package assembly. Invarious embodiments, the package assembly may include a substratecomprising one or more build-up layers, a first die embedded in thesubstrate, a second die, a die interconnect, and an electrical path. Invarious embodiments, the first die may have a first side with one ormore transistors, a second side opposite to the first side, a first TSV,and a first electrical routing feature on the second side. In variousembodiments, the first side may be electrically coupled with the firstelectrical routing feature by the first TSV. In various embodiments, thepackage assembly may further comprise an adhesive layer disposed on thesecond side of the first die. In various embodiments, the second die mayhave a second TSV and a second electrical routing feature electricallycoupled with the second TSV. In various embodiments, the dieinterconnect may be disposed between the first electrical routingfeature and the second electrical routing feature. In variousembodiments, the electrical path may include the first TSV and thesecond TSV, and may be configured to route electrical signals betweenthe second die and the circuit board through the one or more build-uplayers.

In various embodiments, the first die may comprise a microprocessor die.In various embodiments, the first TSV may be one of a first plurality ofTSVs of the first die. In various embodiments, the second die may be aplurality of memory dies arranged in a three-dimensional (3D) stack. Invarious embodiments, the second TSV may be one of a plurality of TSVs ofthe second die that correspond with and are arranged in verticalalignment with the first plurality of TSVs. In various embodiments, asystem may further include an underfill material disposed between thefirst die and the second die. In various embodiments, a system mayfurther include a molding compound disposed to encapsulate the seconddie. In various embodiments, the system may further include one or moreof an antenna, a touch screen display, a touch screen controller, abattery, a global positioning system (GPS) device, a compass, a speaker,a camera, and a mass storage device.

Various embodiments may include any suitable combination of theabove-described embodiments. Furthermore, some embodiments may includeone or more non-transitory computer-readable media having instructions,stored thereon, that when executed result in actions of any of theabove-described embodiments. Moreover, some embodiments may includeapparatuses or systems having any suitable means for carrying out thevarious operations of the above-described embodiments.

The above description of illustrated implementations, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments of the present disclosure to the precise formsdisclosed. While specific implementations and examples are describedherein for illustrative purposes, various equivalent modifications arepossible within the scope of the present disclosure, as those skilled inthe relevant art will recognize.

These modifications may be made to embodiments of the present disclosurein light of the above detailed description. The terms used in thefollowing claims should not be construed to limit various embodiments ofthe present disclosure to the specific implementations disclosed in thespecification and the claims. Rather, the scope is to be determinedentirely by the following claims, which are to be construed inaccordance with established doctrines of claim interpretation.

1. A package assembly comprising: a package substrate with a pluralityof build-up layers; a first die embedded in the package substrate, thefirst die having a first side with one or more transistors, a secondside opposite to the first side, a first through silicon via (TSV), andan electrical routing feature disposed on a first portion of the secondside, wherein the electrical routing feature is electrically coupledwith at least one transistor of the one or more transistors by the firstTSV; an adhesive layer disposed on a second portion of the second sideof the first die; and a second die coupled with the adhesive layer, thesecond die having a second TSV, wherein the second TSV is electricallycoupled with the first TSV.
 2. The package assembly of claim 1, wherein:the second die is a memory die; the electrical routing feature is a TSVpad; the first TSV is one of a first plurality of TSVs of the first die;and the second TSV is one of a second plurality of TSVs of the seconddie that correspond with and are arranged in vertical alignment with thefirst plurality of TSVs.
 3. The package assembly of claim 2, wherein thesecond die is one of a plurality of memory dies configured in athree-dimensional (3D) memory die stack.
 4. The package assembly ofclaim 1, wherein the electrical routing feature is a first TSV pad, thesecond die having a second TSV pad coupled with the second TSV, and thepackage assembly further comprising a die interconnect coupled with thefirst TSV pad and the second TSV pad.
 5. The package assembly of claim1, further comprising an underfill layer disposed between the first dieand the second die.
 6. The package assembly of claim 5, wherein aportion of the underfill layer is disposed between the adhesive layerand the first die.
 7. The package assembly of claim 1, furthercomprising a layer of molding material configured to encapsulate thesecond die.
 8. A method, comprising: providing a first die, wherein thefirst die has a first side with one or more transistors, a second sidewith an electrical routing feature, and a first through silicon via(TSV) coupled to the electrical routing feature and disposed between thefirst side and the second side; coupling an adhesive layer to the secondside of the first die; forming one or more build-up layers on the firstside of the first die; forming an opening in the adhesive layer; andcoupling a second die with the second side of the first die, with theadhesive layer disposed between the first die and the second die,wherein the second die has a second TSV, and wherein the first TSV iselectrically coupled with the second TSV by a conductive path disposedthrough the opening.
 9. The method of claim 8, further comprisingcoupling the adhesive layer to a sacrificial panel prior to coupling theadhesive layer to the second side of the first die.
 10. The method ofclaim 9, wherein forming the opening in the adhesive layer includesforming an opening through the adhesive layer to the sacrificial panelprior to coupling the adhesive layer to the second side of the die, andwherein coupling the adhesive layer to the second side of the dieincludes placing the second side of the die onto the adhesive layer withthe electrical routing feature disposed in the opening.
 11. The methodof claim 10, further comprising: forming a copper layer on thesacrificial panel; and forming a cavity in the copper layer, whereincoupling the adhesive layer to the sacrificial panel includes placingthe adhesive layer into the cavity prior to forming the opening throughthe adhesive layer to the sacrificial panel.
 12. The method of claim 8,wherein coupling the adhesive layer to the second side of the first dieincludes placing a portion of the adhesive layer on the electricalrouting feature, the method further comprising: placing the first dieand the adhesive layer onto a sacrificial panel, with the adhesive layerdisposed between the first die and the sacrificial panel; and removingthe sacrificial panel from the adhesive layer after forming the one ormore build-up layers on the first side of the die, wherein forming theopening in the adhesive layer includes removing the portion of theadhesive layer after removing the sacrificial panel to expose theelectrical routing feature.
 13. The method of claim 8, wherein formingthe opening in the adhesive layer includes exposing a portion of theadhesive layer to laser radiation.
 14. The method of claim 13, whereinexposing the portion of the adhesive layer to laser radiation isperformed by a laser projection patterning tool.
 15. The method of claim13, wherein removing the portion of the adhesive layer further includesscanning the portion of the adhesive layer with an ultraviolet (UV)laser.
 16. The method of claim 8, further comprising applying a moldingmaterial over the second die and the one or more build-up layers,wherein the second die is embedded in the molding material.
 17. Themethod of claim 8, further comprising applying an underfill materialbetween the first die and the second die.
 18. A system, comprising: acircuit board; and a package assembly coupled with the circuit board viaelectrical routing features disposed on an outer surface of the packageassembly, the package assembly comprising: a substrate comprising one ormore build-up layers; a first die embedded in the substrate, the firstdie having a first side with one or more transistors, a second sideopposite to the first side, a first TSV, and a first electrical routingfeature on the second side, the first side electrically coupled with thefirst electrical routing feature by the first TSV; an adhesive layerdisposed on the second side of the first die; a second die with a secondTSV and a second electrical routing feature electrically coupled withthe second TSV; a die interconnect disposed between the first electricalrouting feature and the second electrical routing feature; and anelectrical path including the first TSV and the second TSV, wherein theelectrical path is configured to route electrical signals between thesecond die and the circuit board through the one or more build-uplayers.
 19. The system of claim 18, wherein the first TSV is one of afirst plurality of TSVs of the first die, the second die is a pluralityof memory dies arranged in a three-dimensional (3D) stack, and thesecond TSV is one of a plurality of TSVs of the second die thatcorrespond with and are arranged in vertical alignment with the firstplurality of TSVs.
 20. The system of claim 19, further comprising: anunderfill material disposed between the first die and the second die; ora molding compound disposed to encapsulate the second die